/*
 * Copyright (c) 2014-2017, ARM Limited and Contributors. All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <arch_helpers.h>
#include <assert.h>
#include <css_def.h>
#include <debug.h>
#include <platform.h>
#include <string.h>
#include <utils.h>
#include "css_mhu.h"
#include "css_scpi.h"

#define SCPI_SHARED_MEM_SCP_TO_AP    PLAT_CSS_SCP_COM_SHARED_MEM_BASE
#define SCPI_SHARED_MEM_AP_TO_SCP    (PLAT_CSS_SCP_COM_SHARED_MEM_BASE \
                                 + 0x100)

/* Header and payload addresses for commands from AP to SCP */
#define SCPI_CMD_HEADER_AP_TO_SCP        \
    ((scpi_cmd_t *) SCPI_SHARED_MEM_AP_TO_SCP)
#define SCPI_CMD_PAYLOAD_AP_TO_SCP        \
    ((void *) (SCPI_SHARED_MEM_AP_TO_SCP + sizeof(scpi_cmd_t)))

/* Header and payload addresses for responses from SCP to AP */
#define SCPI_RES_HEADER_SCP_TO_AP \
    ((scpi_cmd_t *) SCPI_SHARED_MEM_SCP_TO_AP)
#define SCPI_RES_PAYLOAD_SCP_TO_AP \
    ((void *) (SCPI_SHARED_MEM_SCP_TO_AP + sizeof(scpi_cmd_t)))

/* ID of the MHU slot used for the SCPI protocol */
#define SCPI_MHU_SLOT_ID        0

static void scpi_secure_message_start(void)
{
    mhu_secure_message_start(SCPI_MHU_SLOT_ID);
}

static void scpi_secure_message_send(size_t payload_size)
{
    /*
     * Ensure that any write to the SCPI payload area is seen by SCP before
     * we write to the MHU register. If these 2 writes were reordered by
     * the CPU then SCP would read stale payload data
     */
    dmbst();

    mhu_secure_message_send(SCPI_MHU_SLOT_ID);
}

static void scpi_secure_message_receive(scpi_cmd_t *cmd)
{
    uint32_t mhu_status;

    assert(cmd != NULL);

    mhu_status = mhu_secure_message_wait();

    /* Expect an SCPI message, reject any other protocol */
    if (mhu_status != (1 << SCPI_MHU_SLOT_ID)) {
        ERROR("MHU: Unexpected protocol (MHU status: 0x%x)\n",
            mhu_status);
        panic();
    }

    /*
     * Ensure that any read to the SCPI payload area is done after reading
     * the MHU register. If these 2 reads were reordered then the CPU would
     * read invalid payload data
     */
    dmbld();

    memcpy(cmd, (void *) SCPI_SHARED_MEM_SCP_TO_AP, sizeof(*cmd));
}

static void scpi_secure_message_end(void)
{
    mhu_secure_message_end(SCPI_MHU_SLOT_ID);
}

int scpi_wait_ready(void)
{
    scpi_cmd_t scpi_cmd;

    VERBOSE("Waiting for SCP_READY command...\n");

    /* Get a message from the SCP */
    scpi_secure_message_start();
    scpi_secure_message_receive(&scpi_cmd);
    scpi_secure_message_end();

    /* We are expecting 'SCP Ready', produce correct error if it's not */
    scpi_status_t status = SCP_OK;
    if (scpi_cmd.id != SCPI_CMD_SCP_READY) {
        ERROR("Unexpected SCP command: expected command #%u, got command #%u\n",
              SCPI_CMD_SCP_READY, scpi_cmd.id);
        status = SCP_E_SUPPORT;
    } else if (scpi_cmd.size != 0) {
        ERROR("SCP_READY command has incorrect size: expected 0, got %u\n",
              scpi_cmd.size);
        status = SCP_E_SIZE;
    }

    VERBOSE("Sending response for SCP_READY command\n");

    /*
     * Send our response back to SCP.
     * We are using the same SCPI header, just update the status field.
     */
    scpi_cmd.status = status;
    scpi_secure_message_start();
    memcpy((void *) SCPI_SHARED_MEM_AP_TO_SCP, &scpi_cmd, sizeof(scpi_cmd));
    scpi_secure_message_send(0);
    scpi_secure_message_end();

    return status == SCP_OK ? 0 : -1;
}

void scpi_set_css_power_state(unsigned int mpidr,
        scpi_power_state_t cpu_state, scpi_power_state_t cluster_state,
        scpi_power_state_t css_state)
{
    scpi_cmd_t *cmd;
    uint32_t state = 0;
    uint32_t *payload_addr;

#if ARM_PLAT_MT
    /*
     * The current SCPI driver only caters for single-threaded platforms.
     * Hence we ignore the thread ID (which is always 0) for such platforms.
     */
    state |= (mpidr >> MPIDR_AFF1_SHIFT) & 0x0f;    /* CPU ID */
    state |= ((mpidr >> MPIDR_AFF2_SHIFT) & 0x0f) << 4;    /* Cluster ID */
#else
    state |= mpidr & 0x0f;    /* CPU ID */
    state |= (mpidr & 0xf00) >> 4;    /* Cluster ID */
#endif /* ARM_PLAT_MT */

    state |= cpu_state << 8;
    state |= cluster_state << 12;
    state |= css_state << 16;

    scpi_secure_message_start();

    /* Populate the command header */
    cmd = SCPI_CMD_HEADER_AP_TO_SCP;
    cmd->id = SCPI_CMD_SET_CSS_POWER_STATE;
    cmd->set = SCPI_SET_NORMAL;
    cmd->sender = 0;
    cmd->size = sizeof(state);
    /* Populate the command payload */
    payload_addr = SCPI_CMD_PAYLOAD_AP_TO_SCP;
    *payload_addr = state;
    scpi_secure_message_send(sizeof(state));
    /*
     * SCP does not reply to this command in order to avoid MHU interrupts
     * from the sender, which could interfere with its power state request.
     */

    scpi_secure_message_end();
}

/*
 * Query and obtain CSS power state from SCP.
 *
 * In response to the query, SCP returns power states of all CPUs in all
 * clusters of the system. The returned response is then filtered based on the
 * supplied MPIDR. Power states of requested cluster and CPUs within are updated
 * via. supplied non-NULL pointer arguments.
 *
 * Returns 0 on success, or -1 on errors.
 */
int scpi_get_css_power_state(unsigned int mpidr, unsigned int *cpu_state_p,
        unsigned int *cluster_state_p)
{
    scpi_cmd_t *cmd;
    scpi_cmd_t response;
    int power_state, cpu, cluster, rc = -1;

    /*
     * Extract CPU and cluster membership of the given MPIDR. SCPI caters
     * for only up to 0xf clusters, and 8 CPUs per cluster
     */
#if ARM_PLAT_MT
    /*
     * The current SCPI driver only caters for single-threaded platforms.
     * Hence we ignore the thread ID (which is always 0) for such platforms.
     */
    cpu = (mpidr >> MPIDR_AFF1_SHIFT) & MPIDR_AFFLVL_MASK;
    cluster = (mpidr >> MPIDR_AFF2_SHIFT) & MPIDR_AFFLVL_MASK;
#else
    cpu = mpidr & MPIDR_AFFLVL_MASK;
    cluster = (mpidr >> MPIDR_AFF1_SHIFT) & MPIDR_AFFLVL_MASK;
#endif  /* ARM_PLAT_MT */
    if (cpu >= 8 || cluster >= 0xf)
        return -1;

    scpi_secure_message_start();

    /* Populate request headers */
    zeromem(SCPI_CMD_HEADER_AP_TO_SCP, sizeof(*cmd));
    cmd = SCPI_CMD_HEADER_AP_TO_SCP;
    cmd->id = SCPI_CMD_GET_CSS_POWER_STATE;

    /*
     * Send message and wait for SCP's response
     */
    scpi_secure_message_send(0);
    scpi_secure_message_receive(&response);

    if (response.status != SCP_OK)
        goto exit;

    /* Validate SCP response */
    if (!CHECK_RESPONSE(response, cluster))
        goto exit;

    /* Extract power states for required cluster */
    power_state = *(((uint16_t *) SCPI_RES_PAYLOAD_SCP_TO_AP) + cluster);
    if (CLUSTER_ID(power_state) != cluster)
        goto exit;

    /* Update power state via. pointers */
    if (cluster_state_p)
        *cluster_state_p = CLUSTER_POWER_STATE(power_state);
    if (cpu_state_p)
        *cpu_state_p = CPU_POWER_STATE(power_state);
    rc = 0;

exit:
    scpi_secure_message_end();
    return rc;
}

uint32_t scpi_sys_power_state(scpi_system_state_t system_state)
{
    scpi_cmd_t *cmd;
    uint8_t *payload_addr;
    scpi_cmd_t response;

    scpi_secure_message_start();

    /* Populate the command header */
    cmd = SCPI_CMD_HEADER_AP_TO_SCP;
    cmd->id = SCPI_CMD_SYS_POWER_STATE;
    cmd->set = 0;
    cmd->sender = 0;
    cmd->size = sizeof(*payload_addr);
    /* Populate the command payload */
    payload_addr = SCPI_CMD_PAYLOAD_AP_TO_SCP;
    *payload_addr = system_state & 0xff;
    scpi_secure_message_send(sizeof(*payload_addr));

    scpi_secure_message_receive(&response);

    scpi_secure_message_end();

    return response.status;
}
